Listen to this:
A recently refoamed pair of 2215H didnīt sound any good (rubbing or scraping voice coils it could be)
When cutting of the dome/dust cap in the center of the cone I discovered some bad thing and there it was, a rotten "vent foam" (I call it vent foam because I donīt have any other name for it)
The foam at the pole pieces vent was factory glued by JBL to prevent dust and debris to reach the magnetic gap. Now they was rottened and had completely fallen to pieces (a paradox??!!) The whole magnetic gap was full of this damn rottened and glue-like black debris so the loudspeakers had to be re coned.
When refoaming old loudspeaker modells with rotten surrounds where there is a vent at the rear of the magnet assembly: check for there is no such foam installed at the pole piece. It could be hard to discover, use a good lamp and look through the vent net at the rear of the magnet. If there is a foam at the pole piece installed, then you have to gently remove the dust cap at the front of the cone and remove the old " vent foam" and clean up the gap/ pole piece
Has anybode had the same experiences ?
By the way, thanks Bo for your excelent " manual" in refoaming. It was/is a god help when refoaming loudspeakers
Best Regards